This proposal is directed toward characterizing the surface membrane of neoplastic lymphocytes in terms of a biochemical and antigenic analysis as well as by various receptor activities. Differences between normal and neoplastic lymphocytes with respect to class of surface Ig expressed, specificity of C3 receptors, and surface antigens will be documented and the relationship between fetal and neoplastic cells explored. Surface receptors, antigens, and other macromolecules will be isolated from both neoplastic and normal cells so that molecular comparisons between normal and neoplastic cells can be made. Antisera to normal T cells, B cells and plasma cells will also be raised, the objective of which is to enable one to characterize immunologic function in terms of these cell types in neoplastic and other disorders involving the immune response and to attempt to use these antisera to specifically inhibit cell mediated or humoral immunity.